Application of a Magnetically Conductive Wedge in the Stator Design of Synchronous Salient-Pole Machines with Fractional-Slot Tooth Winding

Abstract

Often, one of the requirements put forward when designing synchronous machines with electromagnetic excitation is a low shaft speed, but it is not always possible to design a machine with a large number of poles and the required dimensions. The use of fractional-slot tooth winding makes it possible to reduce the number of teeth on the stator, which, in turn, makes it possible to reduce the diameter of the stator bore and design the machine with the required dimensions. In fractional-slot tooth windings, the coil covers one tooth, which makes the process of removing it much easier than in stators with traditional distributed windings, which increases the maintainability of machines with such windings. It is possible to simplify the removal of the coil even more by making the slots completely open, but in this case the influence of stator serration on the distribution of magnetic induction will be stronger than with semiclosed slots, which can lead to a number of negative consequences from increased losses to EMF distortion. In this case, it is possible to reduce the distortion of the magnetic induction curve in the air gap by using a wedge made of magnetically conductive material in the stator design. The article discusses the design of the rotor pole of a salient pole machine with a fractional-slot tooth winding and an open stator slot. In particular, various rotor pole configurations are considered in combination with an open slot stator, a magnetically conductive wedge and without it.